Implantable cardiac stimulation devices are well known in the art. Such devices may include, for example, pacemakers or defibrillators. These devices are generally implanted in an upper portion of the chest beneath the skin of a patient within what is known as a subcutaneous pocket.
Traditionally, therapy delivery has been limited to the right side of the heart. To that end, one or more stimulation leads are implanted within the heart. The leads may include one or more electrodes positioned within the right ventricle or right atrium, or both, of the heart for making electrical contact with their respective heart chambers. Conductors within the leads couple the electrodes to the device to enable the device to deliver the desired cardiac stimulation therapy.
More recently, cardiac stimulation leads and methods have been proposed and even practiced for delivering cardiac stimulation therapy from or to the left side of the heart. These lead structures and methods involve lead implantation within the coronary sinus and/or the great vein of the heart and/or coronary sinus veins, for example, since the coronary sinus is closely adjacent the left atrium and extends into the great vein which is adjacent the left ventricle of the heart. Electrodes thus placed in the coronary sinus and great vein may be used for various forms of cardiac stimulation therapy such as left atrial pacing, left ventricular pacing, and even cardioversion and defibrillation, for example.
Cardiac stimulation lead placement within the left side of the heart can require lead placement in difficult-to-reach veins and arteries. Typically, an outer support sheath is used to cannulate or access the coronary sinus. This sheath or a separate sheath may be then used to access a branch vessel of the coronary sinus (i.e. subselect a vessel). Once the lead is inserted into the coronary sinus or branch vessel, either a solid stylet wire or guidewire is used to advance and guide the lead to its final desired position for optimal clinical performance.
The use of the methods described above present several issues described below:                (a) Use or exchange of outer support sheaths for cannulation and branch vessel selection may result in complications such as lead dislodgement, blood vessel dissection, and prolonged surgery time.        (b) Cardiac stimulation leads are currently designed to use either a stylet or guidewire, but not both concurrently. This requires that a physician exchange one tool for the other in order to navigate tortuous anatomy to the desired final position.        (c) Once the lead is placed, the outer support sheath must be slit or peeled away from the pacing lead in order to remove it from the patient's body since the proximal portion of the lead such as the connector boot and connector seals are typically larger in diameter than the sheath diameter. The need to slit or peel the external sheath increases the surgical procedure time, surgical procedure cost, and probability of surgical complications.        (d) During the procedure, leads designed to allow intraluminal passage of guidewires or stylets also allow blood to flow through the lead and out of the body, clogging the lead lumen and making surgery more difficult. Current lumen seals are undesirable because the friction between the seal and the guidewire or stylet reduces tactile feedback to the implanting physician when advancing the lead, stylet, or guidewire.        
The present invention provides an elegant solution to the aforementioned problems, permitting the concomitant use of both a stylet and a guidewire for implanting a stimulation lead with the additional benefits of intraluminal deflection of the lead and opening of the blood seal. Not only is a lead so adaptable, the adaptation may be easily made, requires minimal components, and may be accomplished with tools already made available to the surgeon.
It was in light of the foregoing known apparatus and techniques that the present invention was conceived and has now been reduced to practice.